1. Field of the Invention
The present invention relates to a multiple power switch module, and in particular such a module useable with a microprocessor to control operation of a domestic laundry appliance.
2. Description of the Prior Art
The prior art is exemplified by U.S. Pat. Nos. 1,146,889 and 3,657,627.
Programmed microprocessor units have wide application in the automatic control of sequentially operated machinery. Such microprocessor units provide output signals in a sequence corresponding to the program to selectively connect electrically operated machinery components to a source of electric potential. Such switching may be accomplished by electronic switches, such as triacs, or mechanically by movement of an actuator to make and break electrical contacts.
In an automatic laundry appliance switches are required to energize and de-energize the appliance motor and solenoids respectively controlling agitate, drain and spin functions, for shifting the appliance through the various cycles of spinning and agitation and to operate solenoids controlling hot and cold water valves, and the solenoids controlling the bleach, detergent and fabric softener dispensers. In the particular application of microprocessor-controlled switching in domestic laundry appliances, such switching has heretofore been of the electronic switch type, with a triac connected between each microprocessor output and the associated electrical component which that output controls, so that upon the appearance of a command signal on the appropriate output line, the triac connects or disconnects the associated electrical component to a source of electrical potential. The reliability of such triac switching is acceptable, however, because triacs are inherently subject to failure due to voltage fluctuations, frequency of use, and other factors, mechanical switching is often preferable.
A problem in the art has been to provide a mechanical switching apparatus for accomplishing a number of relatively high speed switching operations in proper sequence which has comparable speed and accuracy to triac switches.